Dade Hayes Finance EditorQuibi, Jeffrey Katzenberg’s beleaguered mobile streaming startup, got 910,000 people to sign up for free 90-day trials upon its April launch, according to new data from research firm Sensor Tower.The bad news, according to the company: Only 72,000 subscribers stuck around and decided to pay $5 a month (or $8 without ads) for the service, out of 4.5 million total downloads of the app.